The fully brazed heat exchangers of today comprise of brazed packs of plates. A drawback with these brazed heat exchangers are that it is not possible to manufacture large heat exchangers having connections with large inlets and outlets, e.g. with a diameter of about 150 millimeters, in order to increase e.g. the process speed, since the design process pressure, i.e. the maximum process pressure the heat exchanger is designed for, which often is about 150 bar at bursting test, give rise to large forces which can cause the brazings to break and leakage to occur. The leakage can both cause the media in the heat exchanger to be mixed and that one or both of the media leak out from the heat exchanger.
Another type of heat exchanger is the seal type heat exchanger, which is held together by screw joints, with seals between the heat exchanger plates. A drawback with this type of heat exchanger is that they only can be used at low pressures, i.e. at process pressure up to about 50 bar. Further, the heat exchanger seals will age and have to be replaced at regular intervals. Another drawback is that the screw joints are arranged around the heat exchanger in order to hold the plates together, which give rise to large deflections at the connections which in turn leads to leakage in the gaps created due to the deflections.
In order to avoid these problems in a heat exchanger having large dimensions it would require thicker plates having plate thickness about 100 millimeters in order to handle the design process pressure of 150 bar at bursting test, resulting in that a heat exchanger consisting of a number of plates is unpractical and unnecessarily large.
The present invention solves the above problem with leakage from a heat exchanger due to breakage of the brazings in a fully brazed heat exchanger by arranging reinforcement means through the plates around the respective connection, whereby a normal plate thickness of about 2–3 millimeters is sufficient to resist the increased forces.